The present invention relates to the field of communications systems, and more particularly to a method of handling group calls in a communications system, such as in a wireless communications system.
The use of portable wireless communications devices, such as cellular phones, personal communications assistants, and the like, is rapidly increasing throughout society. These wireless communications devices come in a wide variety of configurations, depending on their intended applications. For instance, common cellular telephone mobile terminals attempt to mimic traditional landline telephones, but with additional functionality, such as portability and memorization of large numbers of phone numbers. One trait of landline phones retained in most cellular phones is the ability to engage in full duplex communications. In the typical one-on-one conversation, full duplex operation allows both parties to simultaneously speak, as contrasted with the old prior art of mobile trunked-radio phones which allow only one party to speak at a time. In addition, with conference call or other multi-party capability, more than two parties can typically talk simultaneously. For ease of reference, this full duplex mode of operation will be referred to as xe2x80x9cphone mode.xe2x80x9d The details of phone mode operation in cellular phones are well known in the art.
Some cellular phones are not only capable of operating in phone mode, but also in what will be referred to herein as radio mode. Examples of such dual-mode devices may be seen in U.S. Pat. 5,450,618 and U.S. patent applications Ser. Nos. 09/361,941 and 09/361,747, all of which are incorporated herein by reference, and U.K. Patent Application 9214180.3. In radio mode, the phone appears to the user to handle communications in a half-duplex manner. That is, the cellular phone does not appear to th user as simultaneously transmitting and receiving voice data. Instead, the user must typically push a button known as a push-to-talk (PTT) button in order to include data corresponding to the user""s voice in the data transmitted; otherwise, the phone appears to the user as if it is receiving only. In addition, dual-mode phones typically automatically answer incoming calls when in radio mode.
With increasing frequency, cellular telephones, other mobile terminals, and communications terminals in general are being used for group calls. Group calls are special types of calls where the call originator is trying to communicate with one or more members of a predefined user group. The members of the predefined group may be reached using a wide variety of equipment, such as traditional landline telephones, cellular telephones, satellite telephones, personal communications assistants, pagers, and the like. The most common type of group call is a conference call involving a predetermined plurality of users on a plurality of phones, such as all the engineers on a project. Another type of group call is a broadcast group call from one location to all listening members, such as a group call from a police station to all patrolmen in a given precinct. One common characteristic of group calls is that while less than all the group members may be participating in any given group call, the list of possible participants in the group call other than the originator for the group call (i.e., the group members) is known before the call begins.
As mentioned above, many communications terminals, such as dual-mode phones, typically automatically answer incoming calls in some situations, such as when in radio mode. However, just because the phone answers the call does not necessarily mean that the user is actually attending to the phone. Instead, it is possible that the user has the phone in a mode that auto-answers, such as in radio mode, but has left the unit unattended. If so, then an incoming call may be answered, only to have the originator face the unenviable task of speaking to a phone with no user present. In the context of group calls, this auto-answer feature may present particular problems. It is often desirable for the phone not to auto-answer group calls, or at least certain kinds of group calls. Given this, there is a need for a mechanism by which the communications terminal can determine, prior to answering the call, whether an incoming call is a group call, and optionally some more detailed characteristics of the group call, rather than being a xe2x80x9cnormalxe2x80x9d call. However, there are no known methods for a mobile terminal to determine when the call is group call or is a non-group call (or other aspects of group call). Therefore, there remains a need for a method of indicating to a communications terminal, such as a wireless communications mobile terminal when an incoming call is a group call so that the communications terminal may respond appropriately. Optionally, such a method may also indicate more detailed information about the group call, so that the communications terminal may more finely tune its response to the call.
The present invention supplies certain types of communications terminals with an indication of call type, and optionally other information, for group calls so as to distinguish such calls from other types of incoming calls.
In one typical embodiment, the Group Call Server in charge of the group call selectively augments the calling party number field of the outgoing paging message with one or more indicator flags when the targeted communications terminal is adapted to receive and act upon such information. The indicator flags indicate one or more characteristics of the group call, such as call type, call subtype, or priority level. When the group call server of the present invention receives a group call request, the group call server consults its user group database. The database has records therein corresponding to group members of the requested user group. The records preferably include an indication of the equipment type of the corresponding equipment for each call address (e.g., phone number). When the equipment type is indicated to be of a certain type, or types, corresponding to communications terminals adapted for cooperation with the present invention, (e.g., Enhanced Terminals) the group call server alters the calling party field of the page message to include additional information; otherwise the group call server proceeds as in the prior art. For instance, the group call server can augment the calling party number to add one or more indicator flags. By way of example, a first flag may indicate priority level and a second flag may indicate the call subtype of the group call. In short, the group call server initiates a paging message that includes additional information about the group call for Enhanced Terminals. It is expected that the Enhanced Terminals receiving the augmented paging message will base their response, such as whether to auto-answer or not, on the group call characteristics indicated in the paging message.
In its preferred embodiments, the present invention allows for both the enhanced group call server and the enhanced communications terminals to provide this added functionality while still remaining backwardly compatible with existing installed systems, such as ANSI-136 systems. That is, in preferred embodiments, the present invention relies on already built-in flexibility in existing air interface protocols. As such, the present invention can be implemented without the need to change the signaling and air interface protocols or the BMI (base station, Mobile Switching Center, and Interworking Function).